Community Gardens
Info
Community Gardens can be found all over Singapore.
Unfortunately these are not mapped so you will just have to ask around. Most HDB estates have one nearby.
Some will accept food scraps in their compost pile. They may also welcome surplus garden pots and other 2nd had gardening items. Broken pots are sometimes useful for drainage and other garden uses.
Always ask the gardeners what is permitted in their space.
Accepted Items
Check with your local community garden to see what items they need.